Recently, the treatment in which a stent is placed in a stenosis portion to expand the stenosis portion has been performed in restenotic disorders (tumors, inflammation, and the like) of vessels of living organisms such as blood vessels and the alimentary canal. As examples of the stent, metallic and synthetic resin stents are known. Thereamong, metallic stents require a surgical procedure when being removed from the body, and thus, impose a heavy burden to a patient. Therefore, metallic stents are limited to uses in cases when placement is semi-permanent and cases such as malignant tumors in which a surgical procedure has been planned. Due to these circumstances, a biodegradable stent as a synthetic resin stent has been proposed as the stent which is used in cases in which a metallic stent cannot be used.
The biodegradable stent is formed to a cylinder by knitting biodegradable fibers made of a synthetic resin and decomposes in the blood vessels and the alimentary canal over time, thus, removal of the stent from the body is not necessary. It is anticipated that the biodegradable stent will alleviate the burden to the patent by using, specifically, in benign restenotic disorders.
A stent, generally, expands the stenosis portion by being brought close to and expanding the diameter in the stenosis portion in a reduced diameter state. For example, the method using an endoscope is known as a method for bringing the biodegradable stent close to the stenosis portion. In this method, the stent with the reduced diameter is stored in a thin tube-shaped member which is referred to as a delivery system, and the delivery system is inserted from a forceps port to the inside of the endoscope in order to bring the stent close to the stenosis portion.
Therefore, the stent is brought close to and expands the diameter in the stenosis portion in a reduced diameter state. However, there is the case when the stent, when placed in the stenosis portion, reduces the diameter due to the pressure from the outer side in the radial direction, if the intestinal tract and the like restenoses. Specifically, a biodegradable stent consisting of synthetic resin fibers has a lower strength compared to a metallic stent, and it is difficult to obtain a resistance to the pressure externally applied from the radial direction in an enlarged diameter state sufficient to withstand clinical use.
With respect to this type of problem, the technology for providing a biodegradable stent with resistance to the pressure from the outer side in the radial direction by arranging reinforcing beams extending along the axial direction of the cylinder portion of the biodegradable stent has been disclosed (for example, refer to Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2009-160079